He called for either President Chen Shui-bian or Premier Chang Chun-hsiung to resign in January 2001, as the Executive Yuan had issued an order to end work on the Longmen Nuclear Power Plant without consulting the legislature.

[8][9] After the Judicial Yuan ruled to reduce the committee's powers in December, Yeh stated that "justice was interfering with the legislature.

"[10] He was elected to the National Assembly as a representative of the People First Party in 2005, and subsequently granted a seat on the presidium of its fourth convocation.

[20] He also participated on reviews of martial law,[21] as well as probes of alleged corruption within Taipei City Government regarding the Xinsheng Overpass project and the International Flora Exposition.

[22] In February 2012, Yeh and the Judicial Yuan began investigating Tsai Ing-wen's ties to the former Yu Chang Biologics Company.

[31] In February 2013, he announced the Control Yuan's decision to censure the Ministry of Economic Affairs for its failure to review contracts signed by China Steel, which led to Lin Yi-shih facing accusations of bribery.